Non-cellular adhesive for composite roof structure

ABSTRACT

A composite roof structure, and a corresponding method of fabricating the structure, are disclosed which includes use of a layer of non-cellular adhesive material (preferably a two-component non-cellular polyurea polyurethane adhesive material), roof insulation panels, along with a flexible roof membrane, preferably made of thermoplastic olefin rubber, including a rubber-like sheet having a fleece-like matting secured to the underside thereof. The non-cellular adhesive is preferably sprayed onto a roof substrate and prior to complete solidification thereof the roof membrane or roof insulation is pressed into the adhesive so that the matting becomes embedded therein.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to roof constructions,and more particularly to a composite roof structure and a correspondingmethod for fabricating the composite roof structure, using anon-cellular adhesive material for securing the roof insulation to theroof substrate and an upper, flexible roof membrane comprising a sheetof flexible rubber-like material preferably with fleece-like mattingsecured to the underside thereof or membrane with an underside preparedfor adhesive attachment, to a roof substrate or roof insulation.

[0003] 2. Description of the Prior Art

[0004] Many different roofing systems have been proposed in the past,ranging from simple asphalt/gravel roofs to more sophisticatedstructures making use of synthetic resin materials. It has also beenknown in the past to construct roofs using foamed, cellular adhesivematerials, such as foamed, cellular polyurethane adhesives. However,they present a number of problems. First, the foamed, cellular syntheticresin adhesive materials tend to rise and forms bulges under the roofinsulation or at roof membrane seam areas, thus making difficult andlaborious to control evenness of the finished roof. They provide littleresistance to low temperatures and become friable when are applied attemperature below 40° F. Furthermore, the foamed, cellular syntheticresin adhesive materials have relatively low tensile strength, thusprovide very low puncture resistance to the finished Roof. The foamed,cellular adhesives have limited shelf life.

[0005] It has also been known in the past to construct roofs usingsynthetic rubber membranes formed from EPDM rubber. In suchconstructions, an adhesive substance is first applied to a substrate andallowed to partially dry. This drying causes volatile gases which aremostly pollutants, to escape into the atmosphere. Even at best, Theseroof membranes tend to be poorly attached and many times suffer fromdamage in usually encountered moderate winds.

SUMMARY OF THE INVENTION

[0006] The present invention overcomes the problems outlined above andprovides a greatly improved composite roof structure broadly including alayer of non-cellular adhesive material adapted to be secured to asubstrate, and various insulation layers adhered with the samenon-cellular adhesive along with a flexible roof membrane attached tothe adhesive. The roof membrane includes a sheet of flexible material(e.g. TPO rubber) having a fleece-like matting secured to the undersidethereof or other prepared underside thereof. It has been found that theuse of such matting permits the roof membrane to be strongly adhered tothe adhesive, with the matting being at least partially embedded withinthe adhesive itself.

[0007] In particularly preferred forms, the non-cellular adhesivematerial is in the form of a non-cellular polyurea polyurethane adhesivematerial. The non-cellular adhesive layer has a thickness aftersolidification of at least about {fraction (1/16)} inch, and morepreferably from about {fraction (1/16)} to ¼ inches. Furthermore, inorder to facilitate installation, the non-cellular adhesive material isinitially in the form of a liquid and has a fast initial set andrelatively slow subsequent final cure. Advantageously, the non-cellularpolyurea polyurethane adhesive is a two-component system havingpolyol/diisocyanate components.

[0008] The flexible roof membrane preferably comprises a syntheticrubber (such as TPO, EPDM or the like) sheet having a thickness of fromabout 40-70 mils, with fleece-like non-woven polyester matting having athickness from about 40-80 mils secured thereto or membrane with anunderside prepared for adhesive attachment. While the TPO/polyestermembrane is preferred, the invention is not so limited. Rather, use canbe made of a wide variety of thermoplastic or thermosetting elastomericflexible materials having a selected textile matting (e.g. polyolefinic)secured to the underside thereof or membrane with an underside preparedfor adhesive attachment

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Other objects and advantages of the invention will becomeapparent from a study of the following specification when viewed inlight of the accompanying drawings, wherein:

[0010]FIG. 1 is a schematic view illustrating the application of anon-cellular adhesive material to a roof substrate in the fabrication ofa composite roof structure in accordance with the present invention;

[0011]FIG. 2 is a perspective view of the application of a flexiblemembrane over a layer of the non-cellular adhesive material;

[0012]FIG. 3 is an enlarged vertical sectional view illustrating thecomposite roof structure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0013] The preferred embodiments of the present invention will now bedescribed with the reference to accompanying drawings. Typically, theroofs hereof are applied to an otherwise conventional roof substrate 10which may include metal decking 12 and a layer of insulated foam 14. Inpreparing the substrate, the upper surface thereof should be clean,smooth, dry and free of grease, any sharp edges, fins, loose and foreignmaterials. The temperature of the roof substrate 10 should be 20° F. orabove. Although a metal/insulated foam substrate has been illustrated,it will be appreciated that the invention is not so limited. Thus, thecomposite roof can be directly applied to plywood, chipboard, concrete,or smooth-surfaced built up roofs. The insulation used should becompatible with the adhesive system employed.

[0014] If the substrate is in the form of a ferrous metallic deck, suchshould be primed with an appropriate metallic primer. If a non-ferrousdeck forms the substrate, it should be treated with a wash primer.Substrates of chromate-treated galvanized material should be brushblasted in accordance with SSPC-SP7-63T or acid etched and neutralizedbefore priming. Concrete and/or masonry roof substrates should have aminimum cure of 28 days at 70 degrees F. and 50%, relative humidity. Allsuch surfaces should be clean, dry, and free of all dust, dirt, greaseand oil prior to priming. Where necessary, concrete and/or masonrysurfaces should be brush blasted to the texture of medium gradesandpaper or acid etched with a 10% hydrochloric acid solution andneutralized prior to priming. Where necessary, the concrete and/ormasonry surfaces should be primed with conventional masonry primer. Inthe case of existing built up gravel roofs, the roofs should be powerbroomed in separate perpendicular passes to remove all loose gravel and,where necessary, power vacuumed. All blistered and delaminated ordamaged areas should be removed and insulated foam applied until flushand smooth with the surrounding roof. All loose felts and flashingsshould be mechanically fastened and/or removed.

[0015] After the substrate is prepared, a layer of a non-cellularadhesive material 16 in liquid form is applied. In accordance with thepreferred embodiment of the present invention, a two-componentnon-cellular polyurea urethane adhesive material is used, that includesa mixture of component A, preferably diisocyanate, and component B,preferably polyol. Referring to FIG. 1, it will be seen that use is madeof a conventional two-component spray gun apparatus 18 for this purpose.Where the preferred two-component non-cellular Polyurea polyurethaneadhesive material is used, the polyol and diisocyanate components aremixed within a body of the spray gun apparatus 18 and sprayed onto thesubstrate 10 as illustrated. The temperature of the 1 ambient air orsubstrate should be 20° F. or above. The non-cellular adhesive material16 is applied so as to obtain a final thickness, after completesolidification thereof, of about {fraction (1/16)}-⅛ inch.

[0016] Shortly after the application of the non-cellular polyureapolyurethane adhesive material 16 (as it becomes partially cured), aroof membrane 20 is placed in contact with the adhesive material 16. Itis important that the roof membrane 20 is applied prior to complete setup and solidification of the adhesive material 16. Where the roofmembrane 20 is supplied in a roll form, it can simply be unrolled behindthe spray gun apparatus 18.

[0017] The roof membrane 20 includes an upper flexible rubber sheet 22having a thickness of about 40-70 mils, and a non-woven polyesterfleece-like layer 0.24 secured to the underside of the rubber sheet 22.Preferably, the flexible rubber sheet 22 is made of thermoplastic olefin(TPO) rubber. Alternatively, the flexible rubber sheet 22 may be made ofother appropriate materials, such as ethylene propylene diene monomer(EPDM) rubber. It should be noted, however, that TPO rubber membranesare stronger and more durable than EPDM rubber membranes. Moreover, theTPO rubber membranes are preferred because their membrane seams may bewelded and welded seams are stronger than glued seams. The fleece-likenon-woven, polyester matting preferably has a thickness of about 40-80mils but may be substiyted for any roof membrane bottom surface that hasbeen prepared to receive an adhesive

[0018] After the roof insulation or roof membrane 20 is unrolled andpositioned on the substrate, it is pressed into the adhesive layer bymeans of a roller weighing approximately 100-150 lb to insure insulationcontact or embedment of the fleece-like layer 24. At roof penetrations,the roof membrane 20 is cut as close as possible to the base of thepenetration (in the case of pipes) or “X” cut to allow membrane to turnup onto base flashings.

[0019] As illustrated in FIG. 2, the roof membrane 20 is applied in sideby side strips and thus presents, between respective strips, seam areas26. In order to complete the roof structure, the seam areas 26 of theTPO rubber membranes 20 are welded. Alternatively, when the membranes 20are made of EPDM rubber, a relatively narrow (e.g., 6 inch) seaming tape28 in the form of extruded black rubber tape is employed, which isfactory laminated to the cured EPDM rubber membrane. The tape 28 is softand tacky and is covered with a release liner. The seaming material isapplied to clean, dry membrane sheets, which are aligned with buttededges, as illustrated in FIG. 2. The seaming material is then centeredover the butt joint, making sure there are no bridging areas orwrinkles. The release paper is then stripped from the tape, and lighthand pressure is applied to assure adherence to the underlyingmembranes. The seam is then rolled with a small steel roller (3-4 incheswide) with about 5 pounds per linear inch pressure, 3 passes minimum.Finally, the edges of the applied seaming tape 28 are sealed with a lapsealant in the form of a high-grade roof membrane caulk. Finishingdetails around guttering, snap-on edges or the like are then completed,using conventional techniques.

[0020] As was disclosed hereinabove, the preferred adhesive material 16is the non-cellular two component polyurea urethane system designed forbonding the roof membranes 20 to various acceptable substrates, such asFiberboard, Polyiso, EPS, SPF, Dens Deck, Type X Gypsum, OSB, etc.Compatible deck types include concrete, cellular LWC, gypsum,cementitious wood fiber, wood and painted or galvanized steel. Thenon-cellular two component polyurea polyurethane adhesive material ofthe present invention is also compatible with the following roofingmaterials: smooth BUR, smooth or granulated Mod-Bit and a coal tarpitch.

[0021] The diisocyanate (component A) and polyol (component B)components are mixed in the spray gun apparatus 16 in an approximately1:1 volumetric ratio. The final adhesive, when solidified, has a densityof approximately 67.0 pounds per cubic foot. The polyol componentconsists primarily of a conventional polyol along with surfactants andcatalytic agents. One preferred polyol component includes approximately75% by weight Castor oil, 15% by weight polypropylene glycol, 6% byweight diethyl toluene diamine, 3% by weight ethylene glycol, and 1% byweight desiccant with trace quantities of catalyst. The preferreddiisocyanate component consists of approximately 51% by weight4,4′-methylene diphenyl isocyanate (MDI), 31% by weight polypropyleneglycol, 7% by weight chlorinated paraffin, and 11% by weighttrichloropropyl phosphate. The aforementioned two adhesive componentsare obtained from Volatile Free, Inc. of Waukesha, Wis., and have thefollowing properties and characteristics: TABLE Properties Component AComponent B Base Isocyanate Polymer Polyols, Surfactants and CatalystsMixing Ratios by 1:1 part A to part B Volume Viscosity (CPS@25° C.) 750640 Average Net Weight, 525 438 lbs Packaging 55 gal. Drum 55 gal. DrumShelf Life, years  1  1

[0022] The above disclosed two component non-cellular polyureapolyurethane adhesive material has a high tensile strength in the rangeof 1600 psi (as opposed to relatively low the tensile strength of thecellular polyurethane adhesive material in the range of 75 psi), andprovides the desired properties for application in roof construction,such as low viscosity for ease of application, fast initial cure toprovide a sufficient level of bonding the membrane 18 to the roofsubstrate 10 so that membranes 18 will stay in place, and slow finalcure to ensure that workmen have enough time to apply all membranes tothe roof substrate. These properties are achieved in part by adding afast reacting amine to the adhesive material for providing quick initialset, and the slow curing polyol for providing extended final set time.As was disclosed hereinabove, the preferred adhesive material includesdiethyl toluene diamine. However, the use of other amines, such asisophorone diamine, Ethacure 300, Unilink 4100, Unilink 4200, andClearlink 1000, is also within the scope of the present invention. Thelevel of any amine used is such that partial initial cure is achievedquickly, while final cure to a solid state is delayed for 10 minutes ormore.

[0023] While a two-component non-cellular, polyurea urethane adhesivematerial is preferable, the invention is not so limited. The use canalso be made of other non-cellular adhesive materials, such as a singlecomponent non-cellular polyurea polyurethane adhesive material, ifdesired.

[0024] Therefore, the composite roof structure and method for formingthereof in accordance with the present invention provides manyadvantages in comparison with the prior art.

[0025] First, the non-cellular adhesive material 16 of the presentinvention provides stronger bond between the membranes 20 and the roofsubstrate 10 than foamed, cellular adhesives, because it more thoroughlysaturates the polyester backing 24 on the membrane 20. Thus, superiorwind uplift capability is ensured.

[0026] Secondly, the non-cellular adhesive material 16 of the presentinvention provides higher tensile strength than foamed, cellularadhesives. For instance, the above disclosed preferred two componentnon-cellular polyurea polyurethane adhesive material has a high tensilestrength in the range of 1600 psi compared to the tensile strength ofthe cellular polyurethane adhesive material in the range of 75 psi.Thus, both the bond strength and a puncture resistance of the roofstructure as a whole are substantially improved.

[0027] The non-cellular adhesive material of the present invention isresistant to low temperatures. It may be applied at temperatures up toabout 20° F., whereas the slow rise cellular urethane adhesive cut offis 40° F. Thus, roofing season may be extended. Moreover, unlike thenon-cellular adhesive material, the slow rise cellular urethane adhesivebecomes friable (crystallizes) when it is applied at temperature below40° F., and is destroyed when walked on.

[0028] Furthermore, the non-cellular adhesive material does not risethat makes it easier to control an evenness of the finished roofstructure. The composite roof structure of the present invention has nobulges at the membrane seam areas where additional material is appliedto prevent stress on membrane seams. The even application of theadhesive material to the roof substrate reduces the labor required andtime spent on the membrane seams and other details. Moreover, with thepresent invention, the coverage rate of the roof membranes with thepre-applied fleece backing is approximately from 7,500 to 10,000 squarefeet of roofing, which is substantially higher than the rate ofconventional systems. Accordingly, overall costs are reduced, andaesthetic appearance of the finished roof structure is improved.

[0029] Finally, the non-cellular adhesive material of the presentinvention provides better fire resistance, is less toxic andenvironmentally harmful, and has longer shelf life (1 year compared to 6months for foaming adhesives).

[0030] The foregoing description of the preferred embodiments of thepresent invention has been presented for the purpose of illustration inaccordance with the provisions of the Patent Statutes. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. The embodiments disclosed hereinabove were chosen in order tobest illustrate the principles of the present invention and itspractical application to thereby enable those of ordinary skill in theart to best utilize the invention in various embodiments and withvarious modifications as are suited to the particular use contemplated,as long as the principles described herein are followed. Thisapplication is therefore intended to cover any variations, uses, oradaptations of the invention using its general principles. Further, thisapplication is intended to cover such departures from the presentdisclosure as come within known or customary practice in the art towhich this invention pertains. Thus, changes can be made in theabove-described invention without departing from the intent and scopethereof. It is also intended that the scope of the present invention bedefined by the claims appended thereto.

1. A composite roof structure adapted to be supported by a roofsubstrate and comprising: a layer of non-foamed, non-cellular,two-component synthetic resin adhesive material adapted to be secured tosaid substrate; and a flexible membrane including a sheet of flexiblematerial having an underside for adhesive attachment, said undersideattached to said adhesive material.
 2. (canceled)
 3. (canceled)
 4. Thecomposite roof structure as defined in claim 1, said adhesive materialis non-cellular polyurea polyurethane adhesive material.
 5. Thecomposite roof structure as defined in claim 1, said adhesive materialis non-cellular two component polyurea urethane adhesive material. 6.The composite roof structure as defined in claim 4, said non-cellulartwo component polyurea polyurethane adhesive material including polyoland a diisocyanate components.
 7. The composite roof structure asdefined in claim 1, said layer having a thickness of at least about{fraction (1/16)} inch.
 8. The composite roof structure as defined inclaim 7, said thickness being from about {fraction (1/16)} inch to ¼inch.
 9. The composite roof structure as defined in claim 1, saidadhesive material being initially in the form of a liquid and having aninitial solidification time from about 30 seconds to 5 minutes.
 10. Thecomposite roof structure as defined in claim 1, said sheet of flexiblematerial comprising a synthetic rubber.
 11. The composite roof structureas defined in claim 10, said synthetic rubber being thermoplastic olefinrubber.
 12. The composite roof structure as defined in claim 10, saidsynthetic rubber being ethylene propylene diene monomer rubber.
 13. Thecomposite roof structure as defined in claim 10, said synthetic rubbersheet having a thickness of about 40 mils to 70 mils. 14-15. (canceled)16. A method for forming a composite roof structure upon a roofsubstrate, said composite roof structure comprising a flexible sheethaving an underside for adhesive attachment, said method comprising thesteps of: providing an initially flowable non-cellular adhesivematerial; applying a layer of said initially flowable non-cellularadhesive material onto said substrate; after said adhesive material isapplied, applying a flexible roof membrane thereto by placing theunderside of the membrane in contact with said layer of said adhesivematerial prior to complete solidification thereof and pressing themembrane into the adhesive to insure contact therebetween; and allowingthe adhesive material to solidify.
 17. The method as defined in claim16, wherein said adhesive material is non-foamed, non-cellular syntheticresin material.
 18. The method as defined in claim 17, wherein saidadhesive material is two component non-cellular synthetic resin adhesivematerial.
 19. The method as defined in claim 17, wherein said adhesivematerial is non-cellular polyurea polyurethane adhesive material. 20.The method as defined in claim 18, wherein said adhesive material isnon-cellular two component polyurea urethane adhesive material.
 21. Themethod as defined in claim 20, wherein said non-cellular two componentpolyurea urethane adhesive material including polyol and a diisocyanatecomponents.
 22. The method as defined in claim 18, wherein said layerhaving a thickness of at least about {fraction (1/16)} inch.
 23. Themethod as defined in claim 22, wherein said thickness being from about{fraction (1/16)} inches to ¼ inches.
 24. The method as defined in claim16, wherein said non-cellular adhesive material being initially in theform of a liquid and having an initial solidification time of from about30 seconds to 5 minutes.
 25. The method as defined in claim 16, whereinsaid flexible sheet comprising a synthetic rubber.
 26. The method asdefined in claim 25, wherein said synthetic rubber being thermoplasticolefin rubber.
 27. The method as defined in claim 25, wherein saidsynthetic rubber being ethylene propylene diene monomer rubber.
 28. Themethod as defined in claim 25, wherein said flexible sheet having athickness from about 40 mils to 70 mils. 29-30. (canceled)